Lossless Knowledge Graph Package for:
1) 变量导向定量实证研究方法：系统框架与操作程序
2) 变量导向定量实证研究方法说明

Files included:
- variable_oriented_quantitative_nodes_lossless.csv
  * Node-level table.
  * Contains full, uncut text of both PDF documents in the 'text' field of nodes D1 and D2.
  * Other nodes represent sections, steps, and conceptual/method nodes, linked structurally.

- variable_oriented_quantitative_edges.csv
  * Edge-level table.
  * Encodes document → section, section → subsection/step, document → concept/method,
    and cross-document semantic relations (ELABORATES, SUMMARISES, etc.).

This combination forms a structurally explicit, text-wise lossless knowledge graph for both PDFs.